The value for the LHR_Item_Cost comes from the LHR or the 876-878 $c subfield in the MARC holdings record. This data may include a code for the currency as well as the numerical cost. The report copies out the data into the file, without doing any reformatting.
If you are familiar with Excel, it is possible to remove the extraneous characters:
This will distribute the data in the Item Cost column across the next two to three columns, splitting wherever there is a space. This should leave you with numbers only in the first column, and you will be able to add up the total using Excel's sum function.